Manaka's been on hiatus since April due to ongoing health issues (asthma that she's had since she was a kid which worsened after debuting) and has graduated from the group because of said condition.
http://www.helloproject.com/news/5488/
She wishes to continue somehow, so it sounds like she'll be staying under UF (and maybe H!P?) since there's a chance she'll be able keep being an idol in some way, albeit probably not in a group. She wants to think about what she would like to do and it sounds like she's in talks with UF about future activities. The problem seems to be with travelling around the country and the like.
http://ameblo.jp/countrygirls/entry-12187296025.html